The present invention relates to built laundry detergent compositions containing anionic sulphonate or sulphate surfactants and exhibiting increased mildness to the skin.
Heavy duty laundry detergent compositions have for many years contained an anionic sulphonate or sulphate surfactant, for example, linear alkylbenzene sulphonate (LAS) or primary alcohol sulphate (PAS), as the principal detergent-active ingredient. These anionic surfactants are frequently used in conjunction with ethoxylated alcohol nonionic surfactants which give improved detergency on hydrophobic soils. The nonionic surfactants generally have alkyl chain lengths of C12-C18 and degrees of ethoxylation of 1 to 10.
These anionic and anionic/nonionic surfactant systems are robust and highly efficient on a wide range of soils and under a wide range of conditions, for example, temperature and water hardness. However, they are not noted for mildness to skin. These materials are designed to interact with fatty materials like body soil and protein residues on soiled laundry, and can therefore interact with the skin to give reactions such as dryness and erythema (redness). The milder surfactants used to formulate products intended for prolonged skin contact, for example, shampoos and shower gels, would not perform adequately in heavy duty laundry detergent compositions because of insufficient interaction with fatty materials occurring as soil.
It has now been surprisingly discovered that the mildness to skin of a laundry detergent composition containing an anionic sulphonate or sulphate detergent and a conventional detergent ethoxylated nonionic surfactant can be significantly improved, without detriment to detergency performance, by the incorporation of a low level of a much more highly ethoxylated nonionic surfactant.
GB 2 020 688 (Unilever) discloses a high suds washing powder comprising an active blend of an anionic surfactant and a nonionic surfactant. Only one type of nonionic surfactant in combination with anionic surfactant is disclosed.
U.S. Pat. No. 4,954,292 (Lever Brothers) discloses a detergent composition which comprises anionic surfactant, PVP and a blend of nonionic surfactants. An example is given which discloses, inter alia, Synperonic A3 and A7 together.
WO 94 16052A (Unilever) discloses high bulk density particulate laundry detergent compositions containing low levels (typically below 1 wt %) of a highly ethoxylated long chain alcohol, for example tallow alcohol 80EO, the benefit being improved dissolution.
EP 293 139A (Procter and Gamble) discloses detergent compositions enclosed in two-compartment sachets, the compositions exemplified containing low levels (0.2-0.8 wt %) of tallow alcohol 25EO.
WO 93 02176A (Henkel) discloses the use of highly ethoxylated aliphatic alcohols as xe2x80x9cstructure breakersxe2x80x9d in high bulk density laundry detergent powders containing conventional ethoxylated alcohol nonionic surfactants.
WO 00 08129A (Unilever) discloses mild particulate laundry detergent compositions based on high-foaming anionic surfactant (for example linear alkylbenzene sulphonate) plus one or more milder cosurfactants, for example, amine oxide or cocoamidopropyl betaine.
The present invention provides a built particulate laundry detergent composition comprising
(i) from 5 to 25 wt % of an anionic sulphonate or sulphate surfactant,
(ii) from 1 to 10 wt % of an ethoxylated alcohol nonionic surfactant having an alkyl chain length of from C8 to C18 and an average degree of ethoxylation of from 3 to 10,
(iii) from 1 to 5 wt % of a highly ethoxylated alcohol nonionic surfactant having an average degree of ethoxylation of from 15 to 40,
(iv) from 10 to 80 wt % of detergency builder and
(v) optionally other detergent ingredients to 100 wt %.
The present invention further provides the use of an ethoxylated alcohol nonionic surfactant having an average degree of ethoxylation of from 15 to 40, in an amount of from 1 to 5 wt %, to increase the mildness to skin of a built particulate laundry detergent composition containing an anionic sulphonate or sulphate detergent.